Back in December of 2011, Stratolaunch Systems announced that it was designing a new air launch system for both manned and unmanned spacecraft. Among other things, that system would require the construction of what would be the world’s largest aircraft. While some people might understandably be skeptical of such grand plans ever seeing the light of day, the company recently announced that a couple of important milestones have been reached that bring the project closer to fruition.

You can check out our previous article for a more detailed description of how the Stratolaunch system is designed to work, but here’s the condensed version ...

The spacecraft would be attached to the front end of a 490,000-lb (222,260-kg) multi-stage booster rocket, which would itself be mounted to the underside of the twin-bodied carrier aircraft. That airplane would have a wingspan of over 380 feet (116 m), weigh 1.2 million pounds (544,311 kg), and would be powered by six 747 engines.

The plane would take off from a large airport/spaceport, fly up to the stratosphere, and then release the booster/spacecraft. The booster would subsequently fire its engines, carrying the spacecraft into low-earth orbit.

On March 25th of this year, Stratolaunch Systems announced the completion of the 103,257 square-foot (9,593 sq m) hangar in which the carrier aircraft will be will built. The structure is located at the Mojave Air and Space Port, which is also home to an existing 88,000 sq ft (8,175 sq m) Stratolaunch facility where the plane’s wing and fuselage sections will be fabricated.

Just this Monday, the company went on to announce that it has entered into a partnership with Orbital Sciences Corporation, which will design, build, and operate the booster rocket. Orbital is well-established in the field, having brought us the Antares launch vehicle along with the Pegasus. Like the planned larger-payload Stratolaunch rocket, the Pegasus is also released from an aircraft.

Orbital’s involvement won’t stop with building the rocket, either, as the company will go on to be responsible for the systems engineering of the entire Stratolaunch system. SpaceX had originally been lined up for the rocket-building job, although according to a report in Flightglobal, it dropped out over issues with design changes.

Stratolaunch Systems is the result of a collaboration between philanthropist Paul G. Allen and aerospace expert Burt Rutan. The carrier aircraft is currently being built by Rutan's company Scaled Composites, which also created Spaceship One. It's scheduled to make its first test flight in 2016.

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